An ion exchanger installation has a resin container which is at least partially filled with ion exchanger resin in the form of small resin particles and which exhibits on each of its upper and lower sides at least one liquid conduit emptying into an input or output opening for the addition or drainage of liquids into and out of the resin container, with a water inlet and an acid and/or alkaline inlet to the resin container, with the inlets each exhibiting pipe conduits with cut-off valves, and with a pump for the transport of the liquids.
Such an ion exchanger installation is, for example, known from U.S. Pat. No. 5,108,616 or DE-OS 38 21 036.
In the known ion exchanger installations a fluid charged with unwanted ions, usually salt or lime-containing water, is guided in the operation phase, through the resin container either in the upstream or in the downstream direction and the unwanted ions which are in solution in the liquid are exchanged on the surface of the resin particles with other ions from the ion exchanger resin. When the majority of the exchange ions on the surface of the resin particles are exchanged with the unwanted ions the ion exchanger process becomes ineffective since a noticeable fraction of the unwanted ions remains dissolved in the fluid after the fluid is being treated is passed through the resin container. Therefore after a certain time, or after the passage of a particular volume of fluid which is to be handled through the resin container, the ion exchanger resin is exhausted and must be regenerated. The regeneration agent is effected by introducing a liquid regeneration agent through the ion exchange resin, which for its part, exchanges the unwanted ions, which are bound to the resin particles, with the exchange ions. In the case of a cation exchanger the liquid regenerating agent usually comprises diluted acid, and with an anion exchanger, diluted alkaline solution. In a selective exchanger the ion exchanger resin is initially regenerated with diluted acid and subsequently conditioned with diluted alkaline solution.
In order to, on the one hand, guarantee as complete a regeneration of the exhausted ion exchanger resin as possible while, on the other hand, not wasting the fluid regeneration agent, in known ion exchange installations the liquid regeneration agent is more or less precisely measured, before its introduction into the resin container, with respect to both its degree of dilution with water as well as with respect to its volume amount. Towards this end a plurality of differing methods and apparatuses are known.
In the so-called preparation method a precisely defined volume amount of water and a likewise precisely defined volume amount of concentrated acid or alkaline solution are admeasured in a preparation vessel. Subsequently the fluid is pumped out of the preparation vessel by means of a transport pump and, by means of a return conduit, fed back in again. This circulating pumping procedure is carried out over a certain period of time whereby the concentrated acid or alkaline solution becomes well mixed with the water so that the prepared regenerating agent solution is homogenized in the preparation vessel. Subsequent thereto a defined volume amount of the thereby prepared regeneration agent solution is first transported out of the preparation vessel and into the resin container. Instead of the circulating pumping device a stirring mechanism for the mixing and homogenization of the regeneration agent solution can be provided for. Although, in any event, the preparation method is particularly precise with regard to both the volume amount of liquid regenerating agent introduced into the resin container as well as to its consistency, the required apparative expenditure is significant and the process itself is time consuming and consequently, in general, relatively expensive.
In another method known in the art, the so-called dosage method, a particular volume amount of concentrated acid or alkaline solution is pumped, with the assistance of a dosage pump, out of a relatively small preparation vessel in a time controlled or fill-level controlled fashion and introduced into a stream of water with which the acid or alkaline solution is diluted into liquid regenerating agent which is then introduced into the resin container. Since, with this dosage method, the recirculating pumping device or the mixing mechanism are eliminated the accompanying apparatus is less expensive than that for the preparation method. However, the liquid regenerating agent which is introduced into the resin container can exhibit homogeneity fluctuations as well as, due to time variations in water pressure, variations in the volume amount introduced.
A further disadvantage of the known installation results from the necessity of installing particular safety mechanisms for the mechanical positive displacement pump normally utilized as the dosage pump. Since concentrated acid and alkaline solution are transported with this pump, the system must in any event prevent spill-off of fluids in case of a malfunction. For example, in the event of compressed air failure, conduit blockage due to dirt, or improper adjustment of valves in the conduit system it is necessary to safeguard the transport pump against overheating and a possible leaking which could thereby result or against unacceptable overpressuring which could lead to a rupturing of conduits. These types of safeguarding devices require, however, additional investment and since failures might always occur in the security system, an absolute safeguarding of the installation is impossible.
In contrast, an apparatus which works according to the so-called suction-injector-method is more economical. Here concentrated acid or alkaline solution is introduced, in a time or fill-level controlled fashion, out of a preparation vessel to an ejector constructed in the manner of a Venturi-nozzle through which water, at a particular conduit pressure, is pumped. Since, due to the dynamic partial pressure produced by the ejector, the water carries along with it the concentrated acid or alkaline solution, a dosage pump for the transport of the acid or alkaline solution is not necessary in this known apparatus. The apparatus is therefore more economical than the dosage method apparatus, however, the liquid regenerating agent which is produced in this fashion, is subject to even larger volume and/or density variations which are dependent on the water pressure.
It is therefore the purpose of the present invention to present an apparatus and a method for the regeneration of an ion exchanger installation of the above mentioned kind with which, using simplified apparatus means, a precise dosing and blending of the liquid regeneration agent which is to be introduced into the resin container is nevertheless guaranteed and no special safeguarding devices for the transport pumps are necessary.